The present invention relates to a method and apparatus for introducing liquid agents, such as cleansers and disinfectants, into sanitary facilities, such as water closets.
In addition to disinfectant blocks positioned in the flushing-water inflow of water closets (wc), units which add a cleaning and/or disinfecting liquid to the flushing water either at a certain point in time or continuously are also known.
A unit which can be suspended in a toilet is known, inter alia, from WO 93/03232. The unit sprays an oily liquid into the toilet by way of a straightforward hose pump and is actuated when someone sits on the seat surface (toilet seat). This type of pretreatment is intended to reduce dirt deposits.
The self-cleaning toilet of U.S. Pat. No. 4,183,105 has, in the flushing cistern, a separate container with a cleaning agent which, distributed via the pressure of the water line and spray nozzles cleans the walls of the toilet bowl.
A disadvantage with known devices is that both the point in time at which the liquid is introduced and the quantity of the liquid can only be adapted to a very limited extent to prevailing conditions. The resulting effect may consequently be insufficient. Further consumption of the cleaning agent may be high, as a result of which, if used widely, these units are extremely harmful to the environment.
An improved apparatus is described in EP-A1-579 581. By means of an electronically controlled hose pump, a defined quantity of disinfecting liquid is pumped from a storage container and mixed with incoming flushing water in a mixing chamber. The pumping operation is initiated by a switch which is actuated via a rubber diaphragm which closes off the mixing chamber when the chamber fills with water. The electronic control means assigned to the pump limits the running time of the latter, with the result that the disinfectant is metered within certain limits. During the next flushing operation, the fixture located in the mixing chamber flows into the incoming flushing water; a residual amount, due to the pressure conditions in the pipelines, wets the latter even at the end of the flushing operation, which increases the level of hygiene in the installation.
A disadvantage with such an apparatus is that the hose pump has to operate against the internal pressure of the already water-filled mixing chamber, and that a relatively large quantity of disinfectant is necessary in order to achieve an appropriate effect, at all, since the mixture, which flows in throughout the flushing operation is initially highly diluted.
An object of the present invention is to eliminate the disadvantages of the prior art and to provide an efficient means of controlling and feeding a liquid agent, dependent on the specific requirements of the installation, which results in a minimal, negligible level of harm to the environment, requires minimum maintenance and supplies the liquid agent such that it is provided in the urinal or the toilet before soiling or odors take hold. The liquid is intended to be distributed uniformly and to reach all parts of the facility which may be soiled during normal use.
The foregoing and other objects are met by the method of the present invention which comprises the mixing of the liquid agent with incoming flushing water at a reduced pressure. The pressure of the flushing water is monitored, and the liquid agent is metered into the water at a final time interval during the flushing process. The surfaces wetted by the liquid agent/flushing water mixture are thus completely wetted while the liquid agent is at a low level of dilution, added to the flushing water in a mixing section upstream of the installation.
By monitoring the pressure of the incoming flushing water and the significant drop in pressure which occurs at the end of each flushing operation, the supply of liquid agents can be optimized, with correct timing, while potential harmful effects produced by the agents are minimized.
The present invention makes use of the finding that each non-stationary operation of a sanitary facility has its own characteristics which, in the case of reproducible operations, can also generate reproducible signals which can be used in a particular fashion.
With such recognition, it is possible to determine the ideal point in time for adding a liquid such that it is still distributed in the installation, but is not unnecessarily diluted and/or flushed away by water flowing in after it. The effects of oily emulsions in particular are thus maintained until the installation is next used and prevents, or at least reduces, subsequent soiling of installation to a quite considerable extent.
The method according to the invention is thus very efficient, cost-effective and environmentally friendly. The liquid agent itself may be composed of a wide variety of different, tried and tested active agents which are known per se, and may also include easily degradable wetting agents which adhere particularly well to smooth ceramic surfaces. Even in the case of frequent use in large-scale public toilet facilities, significant amounts of active-ingredient-containing liquid in the downstream sewage system cannot be detected.
Adding the liquid agent to the flushing water at a positive pressure ensures good mixing of the liquid with the flushing water, even with the flushing water pressure decreasing. Providing the liquid agent by suction generated by the flushing water itself is particularly cost-effective and largely maintenance-free.
Monitoring the usage of the facility and controlling the addition of the liquid agent accordingly can help to reduce the usage of the liquid, can increase the maintenance intervals (for replacement of the liquid containers), and can reduce further any harmful effects.
An apparatus in accordance with the invention comprises a storage tank for the liquid agent and a pump for metering the liquid agent into a branch line from the water supply to the sanitary facility. A pressure sensor monitors the branch line and determines flush duration, which is used to time the metering of the liquid in the subsequent flush cycle.
An apparatus of the present invention incorporating a mixing section is particularly favorable for installation in existing facilities, since such a mixing section can easily be integrated in the flushing line, and adapted as a type of intermediate element.
The apparatus of the invention is advantageous in comparison to systems which employ a fixed determination of the drop in pressure, particularly when pressure fluctuations or effects of the building (structure-borne sound, etc.) are to be expected. In addition, it is thus possible for the metering quantity of the liquid to be empirically coordinated with the local requirements.
Arranging the pressure sensor in an intermediate container has proven successful and results in reproducible and easily further processible signal profiles.
A very effective and easy-to-realize way of mixing the liquid in the flushing water is achieved by an ejector. Forming the ejector as a coaxial line to a float or supply line does not require commercially available flushing cisterns to be changed in any way and is thus suitable and easy to implement, in particular for new installations.
A suction-based embodiment is favorable in terms of flow and energy and is additionally very cost-effective to produce and to maintain, since it does not require in any auxiliary energy.